Potato Gratin

1. Preheat the oven to 180 C (350 F) and butter a medium gratin dish, then rub it with one of the halved garlic cloves.
2. Peel the potatoes and slice them thinly and evenly, about 3 mm thick, using a mandoline or sharp knife.
3. Whisk the crème fraîche with the milk, the finely grated zest of the lemon half, the remaining crushed garlic, salt and plenty of black pepper.
4. Fry the pancetta in a dry pan until crisp and golden, then drain on paper towels.
5. Layer the potato slices in the dish, seasoning lightly between layers and pouring over some of the crème fraîche mixture and a little grated gruyère as you go.
6. Pour over any remaining cream mixture, scatter the crisp pancetta and the rest of the gruyère on top, and cover loosely with foil.
7. Bake for 45 minutes, then remove the foil and bake for a further 20 to 25 minutes until the potatoes are tender to the point of a knife and the top is golden and bubbling.
8. Let the gratin rest for 10 minutes before serving so it sets slightly.

You'll use: Oven · Frying pan / skillet · Pan · Large pot · Whisk